lib/ext2fs/openfs.c

   1 /*
   2  * openfs.c --- open an ext2 filesystem
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <fcntl.h>
  19 #include <time.h>
  20 #if HAVE_SYS_STAT_H
  21 #include <sys/stat.h>
  22 #endif
  23 #if HAVE_SYS_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26 #ifdef HAVE_ERRNO_H
  27 #include <errno.h>
  28 #endif
  29
  30 #include "ext2_fs.h"
  31
  32
  33 #include "ext2fs.h"
  34 #include "e2image.h"
  35
  36 blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block,
  37                                      dgrp_t i)
  38 {
  39         int     bg;
  40         int     has_super = 0;
  41         blk64_t ret_blk;
  42
  43         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  44             (i < fs->super->s_first_meta_bg))
  45                 return (group_block + i + 1);
  46
  47         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  48         if (ext2fs_bg_has_super(fs, bg))
  49                 has_super = 1;
  50         ret_blk = ext2fs_group_first_block2(fs, bg) + has_super;
  51         /*
  52          * If group_block is not the normal value, we're trying to use
  53          * the backup group descriptors and superblock --- so use the
  54          * alternate location of the second block group in the
  55          * metablock group.  Ideally we should be testing each bg
  56          * descriptor block individually for correctness, but we don't
  57          * have the infrastructure in place to do that.
  58          */
  59         if (group_block != fs->super->s_first_data_block &&
  60             ((ret_blk + fs->super->s_blocks_per_group) <
  61              ext2fs_blocks_count(fs->super)))
  62                 ret_blk += fs->super->s_blocks_per_group;
  63         return ret_blk;
  64 }
  65
  66 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  67 {
  68         return ext2fs_descriptor_block_loc2(fs, group_block, i);
  69 }
  70
  71 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  72                       unsigned int block_size, io_manager manager,
  73                       ext2_filsys *ret_fs)
  74 {
  75         return ext2fs_open2(name, 0, flags, superblock, block_size,
  76                             manager, ret_fs);
  77 }
  78
  79 /*
  80  *  Note: if superblock is non-zero, block-size must also be non-zero.
  81  *      Superblock and block_size can be zero to use the default size.
  82  *
  83  * Valid flags for ext2fs_open()
  84  *
  85  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  86  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  87  *                              features aren't supported.
  88  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  89  *      EXT2_FLAG_SKIP_MMP - Open without multi-mount protection check.
  90  */
  91 errcode_t ext2fs_open2(const char *name, const char *io_options,
  92                        int flags, int superblock,
  93                        unsigned int block_size, io_manager manager,
  94                        ext2_filsys *ret_fs)
  95 {
  96         ext2_filsys     fs;
  97         errcode_t       retval;
  98         unsigned long   i, first_meta_bg;
  99         __u32           features;
 100         unsigned int    groups_per_block, blocks_per_group, io_flags;
 101         blk64_t         group_block, blk;
 102         char            *dest, *cp;
 103 #ifdef WORDS_BIGENDIAN
 104         struct ext2_group_desc *gdp;
 105         int             j;
 106 #endif
 107
 108         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 109
 110         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 111         if (retval)
 112                 return retval;
 113
 114         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 115         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 116         fs->flags = flags;
 117         /* don't overwrite sb backups unless flag is explicitly cleared */
 118         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 119         fs->umask = 022;
 120         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 121         if (retval)
 122                 goto cleanup;
 123         strcpy(fs->device_name, name);
 124         cp = strchr(fs->device_name, '?');
 125         if (!io_options && cp) {
 126                 *cp++ = 0;
 127                 io_options = cp;
 128         }
 129
 130         io_flags = 0;
 131         if (flags & EXT2_FLAG_RW)
 132                 io_flags |= IO_FLAG_RW;
 133         if (flags & EXT2_FLAG_EXCLUSIVE)
 134                 io_flags |= IO_FLAG_EXCLUSIVE;
 135         if (flags & EXT2_FLAG_DIRECT_IO)
 136                 io_flags |= IO_FLAG_DIRECT_IO;
 137         retval = manager->open(fs->device_name, io_flags, &fs->io);
 138         if (retval)
 139                 goto cleanup;
 140         if (io_options &&
 141             (retval = io_channel_set_options(fs->io, io_options)))
 142                 goto cleanup;
 143         fs->image_io = fs->io;
 144         fs->io->app_data = fs;
 145         retval = ext2fs_get_memalign(SUPERBLOCK_SIZE, 512, &fs->super);
 146         if (retval)
 147                 goto cleanup;
 148         if (flags & EXT2_FLAG_IMAGE_FILE) {
 149                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 150                                         &fs->image_header);
 151                 if (retval)
 152                         goto cleanup;
 153                 retval = io_channel_read_blk(fs->io, 0,
 154                                              -(int)sizeof(struct ext2_image_hdr),
 155                                              fs->image_header);
 156                 if (retval)
 157                         goto cleanup;
 158                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 159                         return EXT2_ET_MAGIC_E2IMAGE;
 160                 superblock = 1;
 161                 block_size = fs->image_header->fs_blocksize;
 162         }
 163
 164         /*
 165          * If the user specifies a specific block # for the
 166          * superblock, then he/she must also specify the block size!
 167          * Otherwise, read the master superblock located at offset
 168          * SUPERBLOCK_OFFSET from the start of the partition.
 169          *
 170          * Note: we only save a backup copy of the superblock if we
 171          * are reading the superblock from the primary superblock location.
 172          */
 173         if (superblock) {
 174                 if (!block_size) {
 175                         retval = EXT2_ET_INVALID_ARGUMENT;
 176                         goto cleanup;
 177                 }
 178                 io_channel_set_blksize(fs->io, block_size);
 179                 group_block = superblock;
 180                 fs->orig_super = 0;
 181         } else {
 182                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 183                 superblock = 1;
 184                 group_block = 0;
 185                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 186                 if (retval)
 187                         goto cleanup;
 188         }
 189         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 190                                      fs->super);
 191         if (retval)
 192                 goto cleanup;
 193         if (fs->orig_super)
 194                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 195
 196 #ifdef WORDS_BIGENDIAN
 197         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 198         ext2fs_swap_super(fs->super);
 199 #else
 200         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 201                 retval = EXT2_ET_UNIMPLEMENTED;
 202                 goto cleanup;
 203         }
 204 #endif
 205
 206         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 207                 retval = EXT2_ET_BAD_MAGIC;
 208                 goto cleanup;
 209         }
 210         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 211                 retval = EXT2_ET_REV_TOO_HIGH;
 212                 goto cleanup;
 213         }
 214
 215         /*
 216          * Check for feature set incompatibility
 217          */
 218         if (!(flags & EXT2_FLAG_FORCE)) {
 219                 features = fs->super->s_feature_incompat;
 220 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 221                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 222                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 223 #endif
 224                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 225                         retval = EXT2_ET_UNSUPP_FEATURE;
 226                         goto cleanup;
 227                 }
 228
 229                 features = fs->super->s_feature_ro_compat;
 230 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 231                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 232                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 233 #endif
 234                 if ((flags & EXT2_FLAG_RW) &&
 235                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 236                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 237                         goto cleanup;
 238                 }
 239
 240                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 241                     (fs->super->s_feature_incompat &
 242                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 243                         retval = EXT2_ET_UNSUPP_FEATURE;
 244                         goto cleanup;
 245                 }
 246         }
 247
 248         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 249             EXT2_MAX_BLOCK_LOG_SIZE) {
 250                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 251                 goto cleanup;
 252         }
 253         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 254                                         EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 255             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 256                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 257                 goto cleanup;
 258         }
 259         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 260         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 261                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 262                 goto cleanup;
 263         }
 264         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 265                 fs->super->s_log_block_size;
 266         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 267             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 268                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 269                 goto cleanup;
 270         }
 271         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 272                                        EXT2_INODE_SIZE(fs->super) +
 273                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 274                                       EXT2_BLOCK_SIZE(fs->super));
 275         if (block_size) {
 276                 if (block_size != fs->blocksize) {
 277                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 278                         goto cleanup;
 279                 }
 280         }
 281         /*
 282          * Set the blocksize to the filesystem's blocksize.
 283          */
 284         io_channel_set_blksize(fs->io, fs->blocksize);
 285
 286         /*
 287          * If this is an external journal device, don't try to read
 288          * the group descriptors, because they're not there.
 289          */
 290         if (fs->super->s_feature_incompat &
 291             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 292                 fs->group_desc_count = 0;
 293                 *ret_fs = fs;
 294                 return 0;
 295         }
 296
 297         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 298                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 299                 goto cleanup;
 300         }
 301
 302         /*
 303          * Read group descriptors
 304          */
 305         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 306         if (blocks_per_group == 0 ||
 307             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 308             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 309            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 310            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 311                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 312                 goto cleanup;
 313         }
 314         fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 315                                                  fs->super->s_first_data_block,
 316                                                  blocks_per_group);
 317         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 318             fs->super->s_inodes_count) {
 319                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 320                 goto cleanup;
 321         }
 322         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 323                                           EXT2_DESC_PER_BLOCK(fs->super));
 324         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 325                                 &fs->group_desc);
 326         if (retval)
 327                 goto cleanup;
 328         if (!group_block)
 329                 group_block = fs->super->s_first_data_block;
 330         if (group_block == 0 && fs->blocksize == 1024)
 331                 group_block = 1; /* Deal with 1024 blocksize && bigalloc */
 332         dest = (char *) fs->group_desc;
 333         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 334         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 335                 first_meta_bg = fs->super->s_first_meta_bg;
 336         else
 337                 first_meta_bg = fs->desc_blocks;
 338         if (first_meta_bg) {
 339                 retval = io_channel_read_blk(fs->io, group_block+1,
 340                                              first_meta_bg, dest);
 341                 if (retval)
 342                         goto cleanup;
 343 #ifdef WORDS_BIGENDIAN
 344                 gdp = (struct ext2_group_desc *) dest;
 345                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 346                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 347                         ext2fs_swap_group_desc2(fs, gdp);
 348                 }
 349 #endif
 350                 dest += fs->blocksize*first_meta_bg;
 351         }
 352         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 353                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 354                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 355                 if (retval)
 356                         goto cleanup;
 357 #ifdef WORDS_BIGENDIAN
 358                 for (j=0; j < groups_per_block; j++) {
 359                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 360                                                 i * groups_per_block + j);
 361                         ext2fs_swap_group_desc2(fs, gdp);
 362                 }
 363 #endif
 364                 dest += fs->blocksize;
 365         }
 366
 367         fs->stride = fs->super->s_raid_stride;
 368
 369         /*
 370          * If recovery is from backup superblock, Clear _UNININT flags &
 371          * reset bg_itable_unused to zero
 372          */
 373         if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 374                                         EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
 375                 dgrp_t group;
 376
 377                 for (group = 0; group < fs->group_desc_count; group++) {
 378                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 379                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 380                         ext2fs_bg_itable_unused_set(fs, group, 0);
 381                 }
 382                 ext2fs_mark_super_dirty(fs);
 383         }
 384
 385         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 386         *ret_fs = fs;
 387
 388         if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) &&
 389             !(flags & EXT2_FLAG_SKIP_MMP) &&
 390             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 391                 retval = ext2fs_mmp_start(fs);
 392                 if (retval) {
 393                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 394                         ext2fs_mmp_stop(fs);
 395                         goto cleanup;
 396                 }
 397         }
 398
 399         return 0;
 400 cleanup:
 401         if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
 402                 *ret_fs = fs;
 403         else
 404                 ext2fs_free(fs);
 405         return retval;
 406 }
 407
 408 /*
 409  * Set/get the filesystem data I/O channel.
 410  *
 411  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 412  */
 413 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 414 {
 415         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 416                 return EXT2_ET_NOT_IMAGE_FILE;
 417         if (old_io) {
 418                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 419         }
 420         return 0;
 421 }
 422
 423 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 424 {
 425         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 426                 return EXT2_ET_NOT_IMAGE_FILE;
 427         fs->io = new_io ? new_io : fs->image_io;
 428         return 0;
 429 }
 430
 431 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 432 {
 433         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 434                 return EXT2_ET_NOT_IMAGE_FILE;
 435         fs->io = fs->image_io = new_io;
 436         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 437                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 438         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 439         return 0;
 440 }